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Free Certified Renewable Energy Professional (REP) exam Practice Questions

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Sample Practice Questions

Try these 10 sample questions from the Certified Renewable Energy Professional (REP) exam practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

  1. 1Before selecting a recycling route for retired PV modules, which property most directly determines whether special material handling is needed?

    1. A.The presence of heavy metals in the cellsCorrect answer: A
    2. B.The modules' former annual electricity yield
    3. C.The array's former DC-to-AC capacity ratio
    4. D.The original installation's tracking configuration

    Explanation: EIA states, "Some types of PV cells contain heavy metals, which require special handling when they are retired." A identifies the relevant material composition. B measures energy production, C describes electrical sizing, and D describes mounting; none establishes the cell materials that determine this handling concern.

    Reference: EIA Solar Energy and the Environment — Manufacturing and materials

  2. 2A passive-solar home in a heating-dominated Northern Hemisphere climate must collect low winter sunlight. Which main glazing orientation best supports that purpose?

    1. A.North-facing
    2. B.South-facingCorrect answer: B
    3. C.East-facing
    4. D.West-facing

    Explanation: DOE Guide to Passive Solar Home Design states, "Windows should face within 30 degrees of true south" South-facing glazing admits low winter sun. North-facing glazing receives less direct winter sun; east and west exposures favor morning and afternoon gains instead of the intended winter-south collection.

    Reference: DOE Guide to Passive Solar Home Design — p.1 Elements / Aperture

  3. 3In a hydropower site assessment, what does hydraulic head describe?

    1. A.Water volume passing per second
    2. B.Vertical elevation difference between headwater and tailwaterCorrect answer: B
    3. C.The horizontal length of the river basin
    4. D.The turbine shaft's rotational speed

    Explanation: DOE QTR Hydropower Technology Assessment states, "Vertical change in elevation, expressed in feet or meters, between the head (reservoir) water level and the tailwater (downstream) level." B defines the available elevation drop. A is flow, C is horizontal distance and D is machinery speed; none measures head.

    Reference: DOE QTR Hydropower Technology Assessment — Glossary / Head

  4. 4Which combination supplies the principal physical ingredients for a conventional hydrothermal electricity resource?

    1. A.Heat, a suitable fluid and permeabilityCorrect answer: A
    2. B.Heat, a suitable fluid and an impermeable flow path
    3. C.Heat, permeability and no mobile heat-transfer fluid
    4. D.A suitable fluid, permeability and no heat gradient

    Explanation: DOE states, "A geothermal resource requires fluid, heat, and permeability to generate electricity." A retains all three. B removes usable permeability, C removes the heat-transport fluid, and D removes the thermal resource; each omits an essential ingredient for the conventional hydrothermal system.

    Reference: DOE Renewable Energy Guidance for Industry: Supplemental Document — p.21 Geothermal Electricity Production

  5. 5In a conventional mass-burn waste-to-electricity plant, what is the immediate use of heat released by burning the waste?

    1. A.Use the furnace directly as a solid-oxide fuel-cell stack.
    2. B.Generate steam for a turbine-generator.Correct answer: B
    3. C.Produce fuel ethanol through bacterial fermentation.
    4. D.Produce syngas in a separate oxygen-restricted gasifier.

    Explanation: EPA states, "The heat released from burning converts water to steam, which is then sent to a turbine generator to produce electricity." B gives the conventional mass-burn boiler pathway. A substitutes electrochemical conversion, C biological fermentation, and D gasification; those are different energy-conversion routes rather than the stated direct-combustion heat use.

    Reference: EPA Energy Recovery from Combustion of Municipal Solid Waste — How combustion energy recovery works

  6. 6What are the principal products when water is split by electrolysis?

    1. A.Methane and carbon dioxide
    2. B.Carbon monoxide and hydrogen
    3. C.Hydrogen and oxygenCorrect answer: C
    4. D.Nitrogen and ammonia

    Explanation: DOE Hydrogen Production: Electrolysis states, "Electrolysis is the process of using electricity to split water into hydrogen and oxygen" C preserves water's hydrogen and oxygen. A and B require a carbon-containing input; D requires nitrogen and a different synthesis process.

    Reference: DOE Hydrogen Production: Electrolysis — Hydrogen Production: Electrolysis / introduction

  7. 7Which storage pairing directly matches each solar technology's output form before an extra electrical-to-heat or heat-to-electric conversion?

    1. A.Electrochemical batteries with PV; thermal storage with CSPCorrect answer: A
    2. B.Thermal storage with PV; electrochemical batteries with CSP
    3. C.Thermal storage with both PV and CSP
    4. D.Electrochemical batteries with both PV and CSP

    Explanation: DOE identifies "electrochemical storage (batteries) with PV plants and thermal storage (fluids) with CSP plants." A matches PV electrical output and CSP thermal output directly. B reverses both native matches, C requires electrical-to-heat conversion for PV, and D requires thermal-to-electric conversion before CSP energy enters a battery. Other couplings are possible with extra conversion; the question specifies direct output-form matching.

    Reference: DOE Solar Integration: Solar Energy and Storage Basics — Types of energy storage

  8. 8A building uses 6,000,000 kBtu/year over 100,000 ft² of gross floor area. What is its annual energy use intensity?

    1. A.60 kBtu/ft²/yearCorrect answer: A
    2. B.0.0167 kBtu/ft²/year
    3. C.600 kBtu/ft²/year
    4. D.6,000,000 kBtu/ft²/year

    Explanation: EPA ENERGY STAR: What Is Energy Use Intensity? states, "dividing the total energy consumed by the building in one year" EUI=6,000,000 kBtu/year÷100,000 ft²=60 kBtu/ft²/year, A. B inverts area/energy, C misplaces one decimal and D omits floor-area normalization.

    Reference: EPA ENERGY STAR: What Is Energy Use Intensity? — EUI calculation

  9. 9What does a renewable portfolio standard generally require from covered electricity providers?

    1. A.A minimum share or amount of covered demand supplied by eligible renewable electricityCorrect answer: A
    2. B.A fixed purchase price for every kWh exported by a renewable generator
    3. C.Retail-rate bill credits for every customer-generator's monthly electricity exports
    4. D.An annual CO2 mass cap applying identically to every generator

    Explanation: EPA defines an RPS as requiring providers to "supply a specified minimum percentage (or absolute amount) of customer demand with eligible sources of renewable electricity." A is the portfolio obligation. B describes a fixed-price purchase approach, C export bill crediting, and D an emissions cap. These are different policy mechanisms rather than the general RPS requirement.

    Reference: EPA Guide to Action: Renewable Portfolio Standards — RPS definition

  10. 10In a controlled local electrical system, what does microgrid island mode mean?

    1. A.The microgrid remains connected and exports while serving its local loads.
    2. B.The microgrid is electrically separated and serves its loads with local resources.Correct answer: B
    3. C.The microgrid is disconnected and all its local resources and loads are shut down.
    4. D.The microgrid remains connected and imports all load energy from the utility.

    Explanation: DOE states, "Microgrids have the flexibility to be either connected to or disconnected from the grid (island mode)." B is local operation after separation. A and D remain grid-connected, and C is shutdown rather than operating island mode.

    Reference: DOE Renewable Energy Guidance for Industry: Supplemental Document — p.29 Microgrids

Exam Review

About Certified Renewable Energy Professional (REP) exam

Certified Renewable Energy Professional (REP) exam · US

Key exam facts

Provider
Association of Energy Engineers (AEE), responsible for the REP certification examination; ProctorU supplies remote proctoring.
Format
Multiple-choice; open book / open notes. In-person or remotely proctored delivery.
Time limit
4 hours of examination time.
Passing score
A passing certification examination result is required. A numeric passing threshold and score scale are not published in the current public REP Scheme 1.0, BoK 1.0 and REP requirements page reviewed.
Exam fee
United States: US$400 combined certification application and examination fee, nonrefundable; US$200 retest fee. Preparatory training is charged separately.

Topics covered

The authority publishes percentage ranges for each content area. The practice percentages below use the midpoint of each range, normalized to 100%; they are not exact percentages published by the authority. Practice question counts may differ slightly because of rounding.

  • Renewable Energy and Environmental Impacts — Official range: 6–10% (Practice allocation: 7.92%)

    • Policies and programs (Agenda 21 + Kyoto Protocol + Paris Agreement)
    • Impacts associated with renewable energy production
    • Comparative assessment of renewable to fossil fuels
    • Environmental Impact of Fossil Fuels and Renewable Energy
    • Cost and benefits of Fossil Fuels and Renewable Energy
    • Primary Energy Consumption Resources
    • Hubbert Peak
    • Impacts of Climate change
    • Approaches to atmospheric carbon mitigation
    • Carbon intensity of fuels
    • Calculating Carbon Emissions Reductions
    • Carbon Emissions and its impact , Carbon Footprints of Energy Applications
    • Carbon management
    • Sox, Nox, Particles, Hg
    • Green House Gases (GHG)
    • Solid Waste
    • Capacity Factors, Power Capacity Penetration

  • Solar Energy — Official range: 11–17% (Practice allocation: 13.86%)

    • Passive solar applications
    • Solar air, heating, cooking, storage, food drying, water distillation
    • High Temperature - Hot water, A/C, Domestic Hot Water - Solar, Thermal
    • Solar hot water heating
    • Solar PV electric generation
    • Concentrated Solar PV
    • Solar thermal electric generation (CSP)
    • Economics and feasibility
    • Calculating Annual Energy Production (AEP) for PV
    • Resource Evaluation PV, Thermal production, GHI Resource Map, DNI Resource Map
    • General Aspects of Mounting and Racking Tracking Systems
    • Pond/lake PV applications

  • Wind Energy — Official range: 10–16% (Practice allocation: 12.87%)

    • Small scale wind turbine generation (WTG) systems
    • Onshore wind energy technologies
    • Offshore wind farms
    • Economics and feasibility (Bentz Limit)
    • Vertical and Horizonal Turbines / Lift and drag
    • Mechanical applications of wind mills and pumps
    • Control Systems - pitching, yaw, emergency shutdown, turbine speed
    • Wind Resource (Map, Classes of Turbines, Wind Shear, risks, turbulence index, wind rose)
    • Calculating AEP
    • Resource Evaluation
    • Capacities and Limitations

  • Hydropower — Official range: 7–11% (Practice allocation: 8.91%)

    • Concept of generation technologies, hydropower basics and hydro resource
    • Large hydro systems
    • Hydro Resource (hydrology cycle, tidal, wave, OTEC)
    • Micro-hydro turbine technologies (low head systems)
    • Pumped storage
    • Estimating power output
    • Ocean Energy Systems (OTEC, Osmotic, Wave Energy, Tidal, Ocean Currents)
    • Economics and feasibility
    • Capacities and Limitations

  • Geothermal Energy — Official range: 6–10% (Practice allocation: 7.92%)

    • Resource Evaluations
    • Geothermal Energy of low enthalpy - Ground source, Heat pumps Applications, Cool tubes, DHW, Horizontal tubes, and Vertical tubes
    • Geothermal Energy of High enthalpy - Electric generation (Direct, flash, binary)
    • Economic and feasibility
    • Calculating Carnot efficiency
    • Geothermal resource
    • Capacities and Limitations

  • Biomass Energy — Official range: 6–8% (Practice allocation: 6.93%)

    • Biomass Resource
    • Biomass thermochemical processes: Combustion, Pyrolysis and Gasification
    • Biofuels (Bioethanol, Biodiesel, 2nd generation biofuel, algae)
    • Biogas anaerobic digesters, municipal solid waste (MSW)
    • Biological mechanical treatment (BMT)
    • Economics and feasibility
    • Capacities and Limitations

  • Waste-to-Energy Systems — Official range: 3–5% (Practice allocation: 3.96%)

    • Waste to energy systems (general)
    • Differences between thermal and non-thermal technologies
    • Waste fuels and their uses
    • Landfill gas and gas turbines and engines
    • Plasma-arc gasification processes (PGP)
    • Economics and feasibility
    • Waste Resource Applicability
    • Capacities and Limitations

  • Hydrogen Applications — Official range: 3–5% (Practice allocation: 3.96%)

    • Sources of Hydrogen
    • Transport and Storage of Hydrogen
    • Fuel cell technologies and micro turbines technologies
    • Differences between low, intermediate and high temperature systems
    • Applications of fuel cell technologies
    • Economics and feasibility
    • Pros and Cons
    • Capacities and Limitations

  • Hybrid Systems — Official range: 4–6% (Practice allocation: 4.95%)

    • Definition and types of hybrid energy systems
    • Benefits of hybrid energy systems
    • How to choose a hybrid system, schematic configurations
    • Pros and cons of a typical solar and wind power combination
    • Pros and cons of a typical pumped-storage and wind combination
    • Capacities and Limitations

  • Energy Storage — Official range: 6–8% (Practice allocation: 6.93%)

    • Types of energy storage (thermal, electrical)
    • Mechanical energy storage systems (pump storage, compressed air, fly wheel)
    • Electrical / electro chemical (compositors, batteries, fuel cells, grid storage)
    • Common Chemical energy storage systems (hydrogen, biofuels, fossil fuels)
    • Thermal energy storage systems (molten salt, seasonal)
    • Comparative capabilities of energy storage systems
    • Energy Storage Calculations
    • Transformation of energy
    • Capacities and Limitations

  • Alternative Energy Strategies for Buildings — Official range: 6–8% (Practice allocation: 6.93%)

    • Energy & Buildings (key terms, energy use, energy flows)
    • Site solutions to optimize alternative energy potential
    • Energy Efficiency & Energy Management
    • Measures of Energy Reduction
    • Demand-side conservation approaches
    • Rating Systems (LEED, Energy Star and others)
    • Integration of renewable energy and alternative energy technologies in buildings
    • Net zero energy and net-positive energy buildings

  • Transportation Systems — Official range: 3–5% (Practice allocation: 3.96%)

    • Strategies for sustainable transportation systems
    • Passive approaches to improving transportation
    • Renewable fuels used in vehicles (ethanol, bio-diesel, algae oil)
    • Gasification and synthetic fuel production for vehicles
    • Renewable electrification for vehicles
    • Hydrogen as a renewable fuel for vehicles
    • General concept programs for renewable transportation
    • Integration Transport and Power Generation Sector

  • Financing and Incentives for Alternative Energy — Official range: 6–10% (Practice allocation: 7.92%)

    • Government Renewable Energy Programs
    • Economic and financial approaches for project justification
    • Basic financial analysis and assessments
    • Life-cycle cost and levelized analysis methodologies
    • Bankability and Risk Assessment
    • Tax considerations (rates, depreciations, etc.)
    • Measurement and verification
    • Financing by combining approaches and incentives

  • Renewable Energy Application for Micro-grids — Official range: 2–4% (Practice allocation: 2.97%)

    • Fundamentals of Micro-grids
    • Central plants vs. distributed generation
    • Virtual Powerplants
    • Smart Grids
    • Smart Energy Networks
    • Interconnection requirements
    • Vehicle to Grid Storage Applications
    • Grid limitations
    • Design considerations such as intermittency and penetration limits

How to prepare

Work through the topics, read the explanation after each answer, and revisit the areas where you miss questions. Use the official outline and reference materials below to guide your study.

These independent practice questions are not actual exam items and do not guarantee a passing result.

Frequently asked questions

What is the exam format?

Multiple-choice; open book / open notes. In-person or remotely proctored delivery.

How long is the exam?

4 hours of examination time.

What is the passing score?

A passing certification examination result is required. A numeric passing threshold and score scale are not published in the current public REP Scheme 1.0, BoK 1.0 and REP requirements page reviewed.

How much does the exam cost?

United States: US$400 combined certification application and examination fee, nonrefundable; US$200 retest fee. Preparatory training is charged separately.

Official sources and references

Confirm current exam arrangements with the exam provider.